EDTA—free mayonnaise and method for the production thereof

ABSTRACT

An EDTA-free mayonnaise having excellent oil oxidation stability can be prepared by incorporating an effective amount of reduced grape juice in combination with a source of acetic acid and egg protein. The invention relates to a method of preparing an EDTA-free mayonnaise, said method comprising incorporating into the mayonnaise reduced grape juice (such as Balsamic vinegar of Modena) in an amount providing 5-2,000 pg gallic acid equivalents per milliliter of aqueous phase; a source of acetic acid in an amount providing 0.2-15% acetic acid by weight of the continuous aqueous phase; and egg protein in an amount of 0.02-4% by weight of the mayonnaise.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method of preparing an EDTA-freemayonnaise, said method comprising incorporating into the mayonnaise acombination of reduced grape juice, a source of acetic acid and protein.

The invention also relates to the use of reduced grape juice as anEDTA-replacer in mayonnaise and to a process of preparing an improvedEDTA replacer from reduced grape juice.

BACKGROUND OF THE INVENTION

Oil oxidation is a undesired process that commonly occurs in oilcontaining food products. If allowed to progress freely, oil oxidationcauses these food products to develop an undesirable, rancid flavour.Unsaturated and especially polyunsaturated fatty acid residues thatabundantly present in vegetable oils are the prime source of rancidsmelling oxidation products.

Oil oxidations are strongly catalyzed by free metal ions, such as ironand copper ions. Traditionally, ethylenediaminetetraacetic acid (EDTA)has been used in food products to prevent oil oxidation and spoilage dueto its capacity to chelate metals. EDTA, however, is a synthetic orartificial ingredient.

Within the food industry an increasing effort is made to removeartificial ingredients from food products and to replace them withnatural alternatives. Owing to its effectiveness, reasonable cost, andlack of viable alternatives, however, EDTA has so far been one of themore difficult artificial ingredients to replace. Attempts so far toreplace or remove EDTA from foods and beverages have yieldeddisappointing results.

U.S. 2010/0028518 describes an oxidatively stable comestible, such as amayonnaise, that is substantially free of EDTA and that comprises aneffective amount of nicotianamine.

U.S. 2010/0159089 describes an oxidatively stable comestible, such as anmayonnaise, that is substantially free of EDTA and that comprises ahydrolyzed polysaccharide having a plurality of side chains withcarboxylic acid groups in an amount effective to provide oxidativestability therein; the polysaccharide is hydrolyzed such that theaverage polysaccharide chain length is about 2 to about 4 molecules andhas an average molecular weight of about 300 to about 900 Daltons.

The use of balsamic vinegar in edible emulsions is known. WO 2010/124870A1, WO 2008/118850 A2, and KR 100 792 811 B1 disclose salad dressingscontaining balsamic vinegar. Also various salad dressings containingbalsamic vinegar are commercially available from supermarkets. However,mayonnaise-type emulsions containing balsamic vinegar are not known.Mayonnaises generally distinguish from salad dressings by being moreviscous and having a pale, slightly yellow colour, and by containingingredients originating from eggs, in particular egg yolk.

It is known that traditional balsamic vinegar has strong antioxidantactivity. This antioxidant activity is related to the positive effectsof the antioxidants in vivo, after consumption of the balsamic vinegar.There is no suggestion to use balsamic vinegar as an ingredient inemulsions to prevent oil oxidation. Tagliazucchi et al. (Journal of FoodBiochemistry, 34 (2010), 1061-1078) observe that during aging oftraditional balsamic vinegar low molecular weight compounds areprogressively incorporated into the melanoidins skeleton and maycontribute significantly to the antioxidant activity ofhigh-molecular-weight melanoidins. According to the authors among thesecompounds, it has been shown that antioxidant phenolic compounds areprogressively incorporated into the melanoidins skeleton during theaging. The authors further conclude that apart from theirbioavailability traditional balsamic vinegar melanoidins andlow-molecular weight antioxidants may exert their effect on thedigestive tract where they can play an important role in protecting thegastrointestinal tract itself from oxidative damage.

Tagliazucchi et al. (European Food Research and Technology, 227 (2008),835-843) describe the extraction of high molecular weight (>10 kDa)melanoidins from traditional balsamic vinegar. Both melanoidins andpolyphenols in traditional balsamic vinegar each contribute about 45% tothe antioxidant activity of the traditional balsamic vinegar.

Verzelloni et al. (Food Chemistry, 105 (2007), 564-571) disclose thatantioxidant activity of the vinegar aqueous fractions that cannot beattributed to phenolic acids is due to the Maillard products or otherantioxidant compounds.

SUMMARY OF THE INVENTION

The inventors have found that an EDTA-free mayonnaise having excellentoil oxidation stability can be prepared by incorporating an effectiveamount of reduced grape juice in combination with a source of aceticacid and egg protein. Thus, one aspect of the invention relates to amethod of preparing an EDTA-free mayonnaise, said method comprisingincorporating into the mayonnaise reduced grape juice in an amountproviding 5-2,000 μg gallic acid equivalents per milliliter of aqueousphase; a source of acetic acid in an amount providing 0.2-15% aceticacid by weight of the continuous aqueous phase; and egg protein in anamount of 0.02-4% by weight of the mayonnaise.

Polyphenols are contained in reduced grape juice in appreciable amounts.The polyphenol content of reduced grape juice can adequately beexpressed in terms of gallic acid equivalents. Consequently, the amountgallic acid equivalents provided by the reduced grape juice is a goodmeasure for the amount reduced grape juice that is used in thepreparation of the mayonnaise.

Besides polyphenols, reduced grape juice contains substantial quantitiesof fructose, glucose, organic acids (e.g. tartaric acid and malic acid)and substances formed during the reduction process, notably melanoidinsand volatile Maillard reaction products (e.g. hydroxymethylfuraldehyde).Melanoidins are brown, high molecular weight heterogeneous polymers thatare the final product of the (heat-induced) Maillard reaction betweenreducing sugars and amino acids.

Melanoidins are formed by cyclizations, dehydrations,retroaldolisations, rearrangements, isomerisations, and condensations ofMaillard reaction products, but none has been fully characterised yet.Therefore it is necessary to apply indirect strategies to assessstructural differences in the melanoidin backbone.

Although the inventors do not wish to be bound by theory, it is believedthat the melanoidins contained in reduced grape juice are capable ofbinding metal cations—such as copper and iron cations—that catalyze theoxidation of unsaturated fatty acids. By binding these metal cations oillipid oxidation can be minimized effectively, provided the melanoidinsare kept away from the oil-water-interface. The latter can be achievedby the incorporation of proteins as proteins tend to accumulate at theoil-water interface, thereby preventing the melanoidin-metal complex tocome into direct contact with the oil droplets.

The invention also relates to an EDTA-free mayonnaise obtainable by theaforementioned method. Also provided is the use of reduced grape juiceas an EDTA-replacer in mayonnaise, said use comprising incorporating thereduced grape juice in the mayonnaise in an amount providing 5-2,000 μggallic acid equivalents per milliliter of aqueous phase.

The invention also relates to an EDTA-free mayonnaise comprising reducedgrape juice in an amount providing 5-2,000 μg gallic acid equivalentsper milliliter of aqueous phase; a source of acetic acid in an amountproviding 0.2-15% acetic acid by weight of the continuous aqueous phase;and egg protein in an amount of 0.02-4% by weight of the mayonnaise.

DETAILED DESCRIPTION OF THE INVENTION

A first aspect of the present invention relates to a method of preparingan EDTA-free mayonnaise that comprises 5-85 wt. % of dispersed oil phaseand 15-95 wt. % of continuous aqueous phase, said method comprisingincorporating into the mayonnaise:

-   -   a reduced grape juice in an amount providing 5-2,000 μg gallic        acid equivalents per milliliter of aqueous phase, said reduced        grape juice containing at least 50% by weight of dry matter of        monosaccharides selected from glucose, fructose and combinations        thereof;    -   a source of acetic acid is incorporated in an amount providing        0.2-15% acetic acid by weight of the continuous aqueous phase,        said source of acetic acid containing at least 20% acetic acid        by weight of dry matter; and    -   egg protein in an amount of 0.02-4% by weight of mayonnaise.

Mayonnaise is generally known as a thick, creamy sauce that can be usedas a condiment with other foods. Mayonnaise is a stable water-continuousemulsion of vegetable oil, egg yolk and either vinegar or lemon juice.Lecithin in the egg yolk is the emulsifier to stably disperse the oil inthe aqueous phase. Many other ingredients can be added to mayonnaise,like herbs, spices, mustard, vegetables, and thickeners. In manycountries the term mayonnaise may only be used in case the emulsionconforms to the ‘standard of identity’, which defines the composition ofa mayonnaise. For example, the standard of identity may define a minimumoil level, and a minimum egg yolk amount. Also mayonnaise-like productshaving oil levels lower than defined in a standard of identity can beconsidered to be mayonnaises. These kind of products often containthickeners like starch to stabilise the aqueous phase. Mayonnaise mayvary in colour, and is generally white, cream-coloured, or pale yellow.The texture may range from of light creamy to thick, and generallymayonnaise is spoonable. In the context of the present invention‘mayonnaise’ includes emulsions with oil levels ranging from 5% to 85%by weight of the product. Mayonnaises in the context of the presentinvention do not necessarily need to conform to a standard of identityin any country.

The term “EDTA-free” as used herein means that the mayonnaise containsless than 10 ppm of ethylenediaminetetraacetic acid (EDTA).

The term “oil” as used herein refers to lipids selected from the groupof triglycerides, diglycerides, monoglycerides, and free fatty acids.The term “oil” encompasses lipids that are liquid at ambient temperatureas well as lipids that are partially or wholly solid at ambienttemperature.

The term “reduced grape juice” as used herein refers to a syrup that hasbeen prepared by boiling grape juice from which seeds and skin have beenremoved until the volume of the juice has been reduced by at least 30wt. % by evaporation. The reduced grape juice of the present inventionis optionally fermented to produce ethanol and acetic acid. Bacteria ofthe genus Acetobacter are capable of converting ethanol into aceticacid.

The term “balsamic vinegar” as used herein refers to a reduced grapejuice that has been fermented to yield a fermented product containing atleast 2 wt. % acetic acid.

The term “acetic acid” as used herein, unless indicated otherwise,refers to free acetic acid in dissociated or protonated form.

Whenever reference is made herein to “gallic acid equivalents” what ismeant is the amount of gallic acid equivalents as determined by theFolin-Ciocalteu assay.

Gallic acid (3,4,5-trihydroxybenzoic acid) is a phenolic acid that isused as a standard for determining the phenol content of variousanalyses by the Folin-Ciocalteu assay.

As suitable Folin-Ciocalteu assay is described by V. L. Singleton et al.(Analysis of total phenols and other oxidation substrates andantioxidants by means of Folin-Ciocalteu reagent, Methods in Enzymology299, 152-178 (1999)). The following is an example of a suitablyprotocol: 20 μL of reduce grape juice samples are pipetted into separatecuvettes. 1.58 mL millipore water and 100 μL Folin-Ciocalteu reagent areadded to the cuvettes. After mixing and waiting for 8 minutes, 300 μL ofa 20 wt % sodium carbonate solution is added. The solutions are leftstanding at 20° C. for 1 hour and absorbance of each solution wasmeasured at 765 nm. A calibration curve is made following the sameprocedure using, for instance, gallic acid solutions at 0, 50, 100, 150,250, 500, 1000, 2500 and 5000 mg/L. Results are reported as Gallic AcidEquivalents.

The Folin-Ciocalteu assay is responsive to any reducing substancepresent in the vinegar. Reducing sugars, tartaric acid, Maillardreaction products, melanoidins, etc. may all cause interferences. Acorrection for the presence of these components can be made by preparinga reference sample containing these components in the same concentrationas the original sample and by subjecting the reference sample to theFolin-Ciocalteu test (as described above). From the absorbance at 765 nmthe correction factor can be determined.

The EDTA-free mayonnaise of the present invention preferably containsless than 5 ppm EDTA, more preferably less than 2 ppm EDTA. Mostpreferably, the EDTA-mayonnaise contains no EDTA.

The benefits of the present invention may be realized in mayonnaise ofvarying oil content. Typically, the mayonnaise contains 10-83 wt. % ofdispersed oil phase and 17-90 wt. % of a continuous aqueous phase. Mostpreferably, the mayonnaise contains 13-82 wt. % of dispersed oil phaseand 18-87 wt. % of a continuous aqueous phase. Together the dispersedoil phase and the continuous aqueous phase typically constitute at least90 wt. %, more preferably at least 95 wt. % and most preferably 100 wt.% of the mayonnaise.

The reduced grape juice that is employed in the present invention may bederived from white or red grapes. The reduced grape juice typically hasa dry matter content of at least 20 wt. %. More preferably, the reducedgrape juice has a dry matter content of 25-95 wt. %, most preferably of30-90 wt. %.

The reduced grape juice is typically incorporated in the mayonnaise inan amount sufficient to provide 1-50 g of dry matter per kg, morepreferably 2-40 g of dry matter per kg, and most preferably 3-25 g ofdry matter per kg of mayonnaise.

The reduced grape juice can be incorporated in the mayonnaise as acomponent of a pre-blend, e.g. a pre-blend of reduced grape juice andthe source of acetic acid. An example of such a pre-blend is a mixtureof reduced grape juice and wine vinegar such as “Balsamic vinegar ofModena”. Balsamic vinegar of Modena is typically prepared by adding redwine vinegar (and optionally flavourings like caramel) to mosto cottofollowed by an aging period of 2-36 months. Usually, the mosto cottorepresents 20-80 wt. % of the latter vinegar.

The water content of the reduced grape juice typically lies in the rangeof 0-78 wt. %. More preferably, the reduced grape juice has a watercontent of 5-75 wt. %, most preferably of 10-70 wt. %.

Examples of reduced grape juices that may be employed in the presentmethod include “Aceto Balsamico Tradizionale” and “mosto cotto”. Mostpreferably, the reduced grape juice is mosto cotto. Mosto cotto containsessentially no acetic acid, notably less than 0.5 wt. % of acetic acid.

The present method of preparing a mayonnaise preferably employs areduced grape juice that contains substantial levels of phenoliccompounds. Typically, the reduced grape juice contains 50-50,000 μg/g,more preferably 300-40,000 μg/g and most preferably 1,000-30,000 μg/ggallic acid equivalents.

Calculated on dry matter the reduced grape juice typically contains0.2-50 mg/g, more preferably 0.5-30 mg/g gallic acid equivalent.

The reduced grape juice is advantageously incorporated in the mayonnaisein an amount providing 10-1,000 μg gallic acid equivalents permilliliter of aqueous phase, more preferably 12-600 μg gallic acidequivalents per milliliter of aqueous phase, and most preferably 15-400μg gallic acid equivalents per milliliter of aqueous phase.

The reduced grape juice has a typical phenolic acid profile. The reducegrape juice typically contains phenolic acids in a concentration of0.03-30 mg per g of dry matter, more preferably of 0.05-20 mg per g ofdry matter and most preferably of 0.1-10 mg/g of dry matter, saidphenolic acids being selected from gallic acid, protocatecuic acid,p-coumaric acid, syringic acid, vanillic acid, 4-hydroxy benzoic acid,feluric acid, caffeic acid and combinations thereof. Typically, each ofthe aforementioned phenolic acids is contained in the reduced grapejuice in an amount of at least 1%, more preferably of at least 2% andmost preferably of at least 3% by weight of the phenolic acids.

Besides phenolic acids, the reduced grape juice typically contains avariety of other substances, such as sugars, pectic substances,proteinaceous matter, organic acids, minerals, caramelization productsand Maillard reaction products. Furthermore the reduced grape juiceusually contains polyphenols such as anthocyanins and tannins.

The reduced grape juice typically contains 60-95%, more preferably70-92% and most preferably 75-90% monosaccharides by weight of drymatter, said monosaccharides being selected from fructose, glucose andcombinations thereof. Calculated on total composition the reduced grapejuice typically contains at least 10 wt. %, more preferably at least 20wt. % and most preferably at least 30 wt. % of the aforementionedmonosaccharides.

Organic acids that are typically contained in reduced grape juice inappreciable amounts include tartaric acid and malic acid. Preferably,the reduced grape juice contains 0.05-4%, more preferably 0.1-2.5% andmost preferably 0.15-1.5% dicarboxylic acids by weight of dry matter,said dicarboxylic acids being selected from tartaric acid, malic acidand combinations thereof.

During the reduction of grape juice heat induced reactions such ascaramelization and Maillard reactions occur. The Maillard reactionsproduce a large variety of volatile substances that contribute to thetypical cooked notes that develop during the reduction. Typical examplesof Maillard reaction products that are formed during the reduction ofgrape juice are furfural, 5-methyl-2-furaldehyde,5-hydroxymethylfuraldehyde, 5-acetoxymethylfurfural and 2-furoic acid.According to a particularly preferred embodiment, the reduced grapejuice contains 50-25,000 mg per kg of dry matter, more preferably80-18,000 mg per kg of dry matter and most preferably 100-15,000 mg perkg of dry matter of Maillard reaction products selected from the groupof furfural, 5-methyl-2-furaldehyde, 5-hydroxymethylfuraldehyde,5-acetoxymethylfurfural, 2-furoic acid and combinations thereof.

The caramelization that inevitably occurs during the reduction of thegrape juice and also subsequent aging cause the reduced grape juice todevelop a very intense, brownish colour, largely because of theformation of melanoidins. As result of this intense colour, applicationof the reduced grape juice in mayonnaise can lead to undesired colouringof the mayonnaise. The inventors have found that it is feasible to atleast partly decolourize the reduced grape juice whilst retaining itsability to prevent undesired lipid oxidation reactions. Suchdecolouration may be achieved very effectively by removing substanceshaving a molecular weight of more than 10 kDa, e.g. by ultrafiltration.Thus, in accordance with a particularly preferred embodiment, thepresent method employs a reduced grape juice that contains less than 0.1wt. %, more preferably less than 0.05 wt. % and most preferably lessthan 0.01 wt. % of substances having a molecular weight of more than 20kDa, especially of more than 10 kDa and most preferably of more than 5kDa. In case the reduced grape juice is used as a component of apre-blend, then the optional removal of substances having a molecularweight of more than 20 kDa from the reduced grape juice may be performedprior or after mixing of the reduced grape juice and the source ofacetic acid.

The reduced grape juice that is preferably used in the method of theinvention that contains less than 0.1 wt. % of substances having amolecular weight of more than 20 kDa preferably is prepared by a processcomprising:

-   -   providing reduced grape juice;    -   filtering the reduced grape juice to remove components having a        molecular weight of more than 20 kDa; and    -   optionally further treating the filtered juice.

Preferably the filtration leads to the removal of substances having amolecular weight of more than 10 kDa and more preferably of more than 5kDa. The filtration makes it possible to use the decoloured reducedgrape juice at appreciable levels in mayonnaise without substantiallyaffecting the colour of the mayonnaise.

As a result of the filtration, the content of components having amolecular weight of more than 20 kDa expressed by weight of dry matteris reduced by at least a factor 2, more preferably by at least a factor5 and most preferably by at least a factor 20.

Typically as a result of filtration, the absorbance at 400 nm isdecreased by at least a factor 5, more preferably by at least a factor 8and most preferably by at least a factor 10.

Additionally the reduced grape juice containing less than 0.1 wt. % ofsubstances having a molecular weight of more than 20 kDa has theadvantage that it has very good anti-oxidative properties, which evenare improved compared to reduced grape juice which does not have areduced level of compounds having a molecular weight of more than 20kDa.

The source of acetic acid that is employed in the present inventionpreferably is a liquid or a powder, most preferably a liquid. The sourceof acetic acid typically contains 50-100%, more preferably 70-98% andmost preferably 80-95% acetic acid by weight of dry matter.

Water typically represents at least 50 wt. %, even more preferably 80-96wt. % and most preferably 85-94 wt. % of the liquid source of aceticacid.

The source of acetic acid employed in the present method usuallycontains only a limited amount of monosaccharides. Typically, the sourceof acetic acid contains less than 3 wt. %, more preferably less than 2wt. % and most preferably less than 1 wt. % monosaccharides selectedfrom fructose, glucose and combinations thereof. Expressed differently,it is preferred that the source of acetic acid contains less than 15%,more preferably less than 12% and most preferably less than 10%monosaccharides by weight of dry matter, said monosaccharides beingselected from fructose, glucose and combinations thereof.

The present method can suitably employ a source of acetic acid that isselected from the group of wine vinegar, sherry vinegar, spirit vinegar,rice vinegar, apple vinegar, malt vinegar and combinations thereof.

The source of acetic acid preferably contains at least 1 wt. %, morepreferably at least 2 wt. % and most preferably at least 4 wt. % ofacetic acid. The acetic acid content of the source of acetic acidtypically does not exceed 60 wt. %.

The source of acetic acid is in an amount providing 0.2-15%, morepreferably 0.2-3% acetic acid by weight of the continuous aqueous phase.

Preferably the weight ratio of reduced grape juice to source of aceticacid ranges from 80:20 to 20:80, more preferred the ratio ranges from80:20 to 40:60.

In order to further improve the oxidative stability of the mayonnaise itcan be advantageous to include a natural anti-oxidant, more particularlya natural anti-oxidant selected from rosemary extract, alpha-tocopherol(vitamin E), ascorbic acid (vitamin C) and combinations thereof.Especially in case the amount of reduced grape juice that is employed inthe mayonnaise is limited (e.g. providing less than 20 g dry matter perkg of mayonnaise), the additional inclusion of a natural anti-oxidant,especially of rosemary extract, can be very advantageous.

In the present method protein is preferably incorporated in themayonnaise in a concentration of 0.05-3%, more preferably of 0.2-2.5%and most preferably of 0.4-2% by weight of mayonnaise.

Egg protein is incorporated in the mayonnaise prepared in the method ofthe invention. In principle any protein can be incorporated in theEDTA-free mayonnaise that is capable of promoting the formation of anoil-in-water emulsion. Preferably, an additional protein is selectedfrom the group consisting of dairy protein, legume protein andcombinations thereof. Even more preferably, an additional protein iswhey protein.

The dispersed oil phase of the mayonnaise that is produced by thepresent method typically has a volume averaged geometric-mean diameterof 0.5-20 μm, more particularly of 2-7 μm. The volume averaged geometricmean diameter (D_(3,3)) of the dispersed phase is suitably determined bymeans of the NMR method described by Van Duynhoven et al. (Eur. J. LipidSci. Technol. 109 (2007) 1095-1103).

The mayonnaise typically contains 0.5-10 wt. %, more preferably 2-8 wt.% and most preferably 3-7 wt. % egg yolk. Here the weight percentagerefers to ordinary ‘wet’ egg yolk. It should be understood that theinvention also encompasses the use of lyophilized egg yolk in equivalentamounts.

Preferably an additional oil-in-water emulsifier is incorporated in themayonnaise prepared according to the method of the invention. Thepresence of such emulsifier may further enhance the oxidative stabilityof the oil. Emulsifier molecules at the oil-water interface may keepmetal atoms away from the interface. These metal atoms, notably iron,are known to promote oil oxidation. The metal atoms may be bound toother ingredients in the composition, for example they may be bound tomelanoidins originating from the reduced grape juice. Preferredemulsifiers are phospholipids and polyoxyethylene sorbitan monostearate,or a combination of both. The amount of the emulsifier preferably rangesfrom 0.1 wt. % to 2 wt. %, preferably from 0.2 wt. % to 1.5 wt. %,preferably from 0.3 wt. % to 1 wt. % by weight of the mayonnaise.

Another aspect of the present invention relates to an EDTA-freemayonnaise that is obtainable by the method described herein before.Even more preferably the EDTA-free mayonnaise is obtained by saidmethod.

Another aspect of the present invention relates to an EDTA-freemayonnaise that comprises 5-85 wt. % of dispersed oil phase and 15-95wt. % of continuous aqueous phase, further comprising:

-   -   reduced grape juice in an amount providing 5-2,000 μg gallic        acid equivalents per milliliter of aqueous phase, said reduced        grape juice containing at least 50% by weight of dry matter of        monosaccharides selected from glucose, fructose and combinations        thereof;    -   a source of acetic acid in an amount providing 0.2-15% acetic        acid by weight of the continuous aqueous phase, said source of        acetic acid containing at least 20% acetic acid by weight of dry        matter; and    -   egg protein in an amount of 0.02-4% by weight of the mayonnaise.

Preferably the reduced grape juice contains less than 0.1 wt. %, morepreferably less than 0.05 wt. % and most preferably less than 0.01 wt. %of substances having a molecular weight of more than 20 kDa, morepreferably of more than 10 kDa, more preferably of more than 5 kDa.

Preferred embodiments disclosed in the context of the method of theinvention, are applicable to this aspect of the invention, providing anEDTA-free mayonnaise, mutatis mutandis.

A further aspect of the invention relates to the use of reduced grapejuice as an EDTA-replacer in mayonnaise comprising 5-85 wt. % ofdispersed oil phase and 15-95 wt. % of continuous aqueous phase, saiduse comprising incorporating the reduced grape juice in the mayonnaisein an amount providing 5-2,000 μg gallic acid equivalents per milliliterof aqueous phase, more preferably in an amount providing 10-600 μggallic acid equivalents per milliliter of aqueous phase and mostpreferably in an amount providing 15-400 μg gallic acid equivalents permilliliter of aqueous phase. Preferably the reduced grape juice containsless than 0.1 wt. %, more preferably less than 0.05 wt. % and mostpreferably less than 0.01 wt. % of substances having a molecular weightof more than 20 kDa. Preferably the reduced grape juice contains lessthan 0.1 wt. %, more preferably less than 0.05 wt. % and most preferablyless than 0.01 wt. % of substances having a molecular weight of morethan 10 kDa and more preferably of more than 5 kDa. Preferably thereduced grape juice contains at least 50% by weight of dry matter ofmonosaccharides selected from glucose, fructose and combinationsthereof.

Yet another aspect of the invention relates to a process of preparing anEDTA replacer, said process comprising:

-   -   providing reduced grape juice;    -   filtering the reduced grape juice to remove components having a        molecular weight of more than 20 kDa; and    -   optionally further treating the filtered juice.

Preferably the reduced grape juice is filtered to remove componentshaving a molecular weight of more than 10 kDa, more preferably of morethan 5 kDa. As explained herein before, the removal of components havinga molecular weight of more than 10 kDa effectively reduces the colourintensity of the reduced grape juice and makes it possible to use thethus decoloured reduced grape juice at appreciable levels in mayonnaisewithout substantially affecting the colour of the mayonnaise.

As a result of the filtration, the content of components having amolecular weight of more than 20 kDa expressed by weight of dry matteris reduced by at least a factor 2, more preferably by at least a factor5 and most preferably by at least a factor 20. Preferably the content ofcomponents having a molecular weight of more than 10 kDa expressed byweight of dry matter is reduced by at least a factor 2, more preferablyby at least a factor 5 and most preferably by at least a factor 20. Morepreferably the content of components having a molecular weight of morethan 5 kDa expressed by weight of dry matter is reduced by at least afactor 2, more preferably by at least a factor 5 and most preferably byat least a factor 20. Preferably the filtered reduced grape juicecontains less than 0.1 wt. %, more preferably less than 0.05 wt. % andmost preferably less than 0.01 wt. % of substances having a molecularweight of more than 20 kDa, more preferably of more than 10 kDa, morepreferably of more than 5 kDa.

Typically as a result of filtration, the absorbance at 400 nm isdecreased by at least a factor 5, more preferably by at least a factor 8and most preferably by at least a factor 10.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLES Example 1

Mayonnaise samples were prepared in 200 g batches on the basis of therecipes (in wt. %) shown in Table 1.

TABLE 1 1 2 3 4 Oil 76 76 76 76 Balsamic vinegar 5 Cooked must 4 Spiritvinegar 2.5 2.5 2.5 0 EDTA 0.008 Sugar 1.3 1.3 1.3 1.3 Salt 0.7 0.7 0.70.7 Egg yolk 3.9 3.9 3.9 3.9 Mustard oil 0.3 0.3 0.3 0.3 Water 15.3 15.311.3 12.8

-   -   The balsamic vinegar was an “Aceto balsamico di Modena I.G.P.”        obtained from Acetum, Italy. This vinegar is a blend of 80 wt. %        dry cooked must and 20 wt. % wine vinegar and had been aged for        36 months. The specification of this balsamic vinegar is as        follows:        -   a Total acidity (acetic acid): 6.00-6.15 g/100 ml        -   pH 2.0-3.5        -   Total dried extract 700-850 g/l        -   Total sugars 600-720 g/l    -   The content of phenolic compounds in this balsamic vinegar has        been determined using the Folin Ciocalteu assay. The vinegar        contains about 4550 μg gallic acid equivalents per milliliter;        this number has been obtained after correction for the presence        of reducing sugars (about 150 μg/ml GAE).    -   The cooked must is the same dry cooked must that is contained in        the balsamic vinegar (but not aged).

The mayonnaise samples were prepared using the following procedure:

-   -   The egg yolk (5° C.), water-soluble ingredients, water and        vinegar were mixed manually and added in a mixing bowl.    -   An oil phase consisting of soy bean oil and mustard oil was        slowly added to the aqueous phase using a high speed mixer        (Silverson, 3000 rpm). After addition of the oil phase mixing        continued for 4 minutes at a higher stirrer speed (7000 rpm).

The pH of the samples was measured after 1 day and, if necessary,adjusted to pH 3.9.

All samples were subjected to an accelerated storage test followed byvolatile analysis using the following procedure:

-   -   Approximately 20 gram emulsion was distributed among 20        headspace vials (Chrompack, 20 ml). The sample vials were capped        and placed in an oven at 50° C. in the dark. The samples were        left in the oven without stirring or mechanical agitation.    -   Triplicate samples were removed from the oven at regular time        intervals and cooled down to ambient temperature in the dark.        The samples were decapped and flushed for ca. 6 seconds with a        nitrogen stream at a flow rate of 500 ml/min to prevent further        oxidation. The samples are re-capped and stored at −20° C. until        further analysis.    -   Samples oxidised for various lengths of time were collected for        headspace analysis using a GC-17A gas chromatograph (Shimadzu).        The samples were placed in an automated headspace sampler at        40° C. and allowed to equilibrate for at least 30 minutes.        Headspace samples (0.25 ml) were taken with a gas-tight syringe        and injected in split mode (ratio 1:20) onto a DB Wax column        (J&W Scientific). Column specifications: length 20 m, diameter        0.18 mm and film thickness 0.3 mm. The chromatograph was        equipped with a flame ionization detector. Temperatures at the        inlet and detector were 200° C. and 280° C., respectively. The        temperature programming for gas chromatographic analysis was:        33° C. (2 min)-35° C./min to 200° C.-200° C. (2 min). Gas flow        (helium) through the column was at 1.0 ml per minute.    -   Samples were measured in random order to avoid systematic errors        due to e.g. carry over effects. Peak areas (in μV·s) were        quantified for the following oxidation off-flavours:        acetaldehyde, propenel, propanel, pentane, 2t-butenal,        1-penten-3-one, 1-penten-3-ol, pentanal, 2t-pentenal and        hexanal. Peak areas of triplicate samples were averaged.

Hexanel is a typical oxidation volatile and used as an indicator ofoxidative stability. The lower the amount of volatiles, the less oiloxidation has occurred. Table 2 shows the hexanal levels found in theheadspace of the emulsions at different stages of the acceleratedoxidation test.

TABLE 2 Time (in days) 1 2 3 4 0 3,131 3,495 1,648 2,913 3 3,111 12,4993,891 6,103 6 3,725 26,879 8,360 9,702 8 7,954 39,221 6,617 8,188 1013,842 50,770 7,944 12,043 13 6,392 71,650 11,306 17,050 15 9,948 70,28513,528 12,655 17 11,213 83,211 9,685 16,786 20 20,654 164,129 19,30819,730 22 17,628 260,949 16,509 18,184 24 37,719 689,574 24,217 32,52827 49,338 1,022,440 32,412 34,873 29 66,364 769,767 41,163 42,990 3168,573 946,349 48,335 83,213 34 134,795 1,298,420 63,108 112,628

Similar results were obtained for the other volatiles detected, such aspentane, pentanal or pentene-3-one.

Example 2

Mayonnaise samples were prepared in 200 g batches on the basis of therecipes described in Table 3 (in wt. %), using the procedure describedin example 1.

TABLE 3 1 2 3 4 Oil 76 76 76 76 Balsamic vinegar 1.5 1.5 Rosemaryextract 0.1 Spirit vinegar 2.5 2.5 1.75 1.75 EDTA 0.008 Sugar 1.3 1.31.3 1.3 Salt 0.7 0.7 0.7 0.7 Egg yolk 3.9 3.9 3.9 3.9 Mustard oil 0.30.3 0.3 0.3 Water 15.3 15.3 14.55 14.45

-   -   The balsamic vinegar was the same as in example 1.    -   The rosemary extract (Guardian rosemary extract 201) was        obtained from Danisco.

All samples were subjected to the accelerated storage test and volatileanalyses as described in example 1.

Table 4 shows the hexanal levels found in the headspace of the emulsionsat different stages of the accelerated oxidation test.

TABLE 4 Time (in days) 1 2 3 4 0 1,062 1,349 1,207 366 2 556 40,3366,567 4,772 5 3,665 530,070 25,277 18,646 7 5,849 1,299,915 36,05520,996 9 11,620 2,702,457 51,462 29,094 12 25,656 2,979,348 238,33347,108 14 33,815 3,555,168 788,956 56,602 16 89,466 3,187,306 1,815,04692,968 19 257,708 3,895,275 2,412,717 171,258 21 396,588 3,068,1762,304,786 786,859 23 — 3,535,352 1,874,919 791,812 26 923,902 3,482,7332,156,975 1,823,567 28 3,276,075 4,402,565 2,701,923 1,742,624

Example 3

The balsamic vinegar described in example 1 was used as a startingmaterial for the isolation of a high molecular fraction (HMW) and a lowmolecular fraction (LMW).

The HMW fraction was prepared by alcohol precipitations as follows:

-   -   Ethanol (pure) was slowly added to balsamic vinegar while        stirring. Ratio: 70% ethanol, 30% balsamic vinegar (on weight)    -   Ethanol/balsamic vinegar mixture was equilibrated for 15 hours        at room temperature    -   Mixture was centrifuged at 15.000×g during 15 min    -   Sediment (=precipitated melanoidins+low molecular weight sugars)        was collected    -   Sediment was redispersed into millipore water    -   Low molecular weight sugars (fructose, glucose) were removed by        ultrafiltration (Amicon, 3 kDa filter, regenerated cellulose)    -   Ultrafiltration procedure was repeated 2×    -   Retentate was lyophilized

Seventeen grams of balsamic vinegar yielded one gram of lyophilized HMWfraction.

The LMW fraction was prepared by subjecting the balsamic vinegar toultrafiltration, using the same ultrafilter used in the isolation of theHMW fraction and by recovering the permeate.

The balsamic vinegar and the fractions obtained therefrom were used inthe preparation of mayonnaise samples on the basis of the recipesdescribed in Table 5 (in wt. %), using the procedure described inexample 1. Again, EDTA-free and EDTA-containing control samples wereincluded in the experiment.

TABLE 5 1 2 3 4 5 Oil 76 76 76 76 76 Spirit vinegar 2.5 2.5 0 2.5 0Balsamic vinegar 5 Balsamic vinegar (HMW) 0.25 Balsamic vinegar (LMW) 5EDTA 0.008 Sugar 1.3 1.3 1.3 1.3 1.3 Salt 0.7 0.7 0.7 0.7 0.7 Egg yolk3.9 3.9 3.9 3.9 3.9 Mustard oil 0.3 0.3 0.3 0.3 0.3 Water 15.3 15.3 12.815.05 12.8

Visual observation showed that sample 5 had a lighter colour than sample3. All samples were subjected to the accelerated storage test andvolatile analyses as described in example 1.

Table 6 shows the hexanel levels found in the headspace of the emulsionsat different stages of the accelerated oxidation test.

TABLE 6 Time (in days) 1 2 3 4 5 0 3,131 3,495 2,913 3,624 2,239 3 3,11112,499 6,103 13,062 5,303 6 3,725 26,879 9,702 28,254 6,765 8 7,95439,221 8,188 35,766 5,711 10 13,842 50,770 12,043 51,133 15,348 13 6,39271,650 17,050 47,820 12,034 15 9,948 70,285 12,655 98,761 15,067 1711,213 83,211 16,786 96,283 20,241 20 20,654 164,129 19,730 175,22918,743 22 17,628 260,949 18,184 207,718 19,846 24 37,719 689,574 32,528727,382 31,756 27 49,338 1,022,440 34,873 748,862 37,791 29 66,364769,767 42,990 735,513 48,224 31 68,573 946,349 83,213 576,816 54,765 34134,795 1,298,420 112,628 1,770,213 82,653

Example 4

Three different emulsions were prepared in 100 gram batches on the basisof the recipes shown in Table 7 (in wt. %).

TABLE 7 1 2 3 sunflower oil 10 10 10 balsamic vinegar 45 45 whitevinegar 45 Tween 60 0.9 0.9 millipore water 44.1 44.1 45

-   -   The balsamic vinegar was an Aceto balsamico di Modena I.G.P.        obtained from Acetum, Italy. This balsamic vinegar was made from        a cooked grape must similar to the one contained in the balsamic        vinegar that was used in the previous examples. The balsamic        vinegar had been prepared from cooked grape must (40%) and red        wine vinegar (60%) and had been aged for a period of at least 2        months in oak barrels. The balsamic vinegar contained 6% acetic        acid, 25-30 wt. % sugars and 3229 μg gallic acid equivalents per        milliliter (corrected for the presence of reducing sugars,        approximately 100 μg/ml GAE).    -   The white spirit vinegar (6% acetic acid) was obtained from        Kühne Benelux BV (The Netherlands).    -   Tween 60 (polyoxyethylene sorbitan monostearate) was obtained        from Acros Organics.

The emulsions were prepared as follows:

-   -   Tween 60 was first dissolved in millipore water at a        concentration of 2% by weight. 10 gram sunflower oil was then        dispersed in 45 gram of the Tween 60 solution using a high shear        mixer (Silverson, 7000 RPM, 10 minutes). The emulsion obtained        was then mixed with 45 gram balsamic vinegar (sample 1) or 45        gram white vinegar (sample 2). Mixing was performed manually        with a spatula for 5 minutes.    -   Sample 3 did not contain Tween 60. In this case 10 gram        sunflower oil was dispersed directly in 45 gram balsamic vinegar        using a Silverson mixer (7000 RPM, 10 minutes). The emulsion was        then mixed manually with 45 gram millipore water.    -   pH of the samples was adjusted to 3.8 using 1 N NaOH. A small        increase of pH was observed after equilibration of the samples.

All samples had a pH of approximately 3.9 and an oil droplet size(Sauter mean diameter D_(3,2)) of about 5 μm.

All samples were subjected to an accelerated storage test followed byvolatile analysis. The volatile analysis was carried out as described inexample 1. The accelerated storage test only differed from theaccelerated storage test described in example 1 in that the samples werekept at 60° C. instead of 50° C. and in that duplicate rather thantriplicate samples were analysed.

Table 8 shows the hexanal levels found in the headspace of the emulsionsat different stages of the accelerated oxidation test.

TABLE 8 Time (in hours) 1 2 3 0 749 372 1,504 24 10,816 12,390 23,677 4824,234 71,485 79,488 68 36,633 126,472 224,059 92 54,142 849,512 733,857116 55,079 1,587,410 1,508,078 142 84,644 1,654,434 1,717,709 168247,712 1,699,034 1,904,078 240 1,072,620 1,609,590 1,929,993 3081,539,688 1,815,592 2,650,217

Similar results were obtained for the other volatiles detected, such aspentane, pentanel or pentene-3-one.

Metal ion content is one of the important factors controlling lipidoxidation in emulsions. The balsamic vinegar used in this experimentcontained a relatively high amount of iron (ca. 10 mg/kg). The whitevinegar had a significantly lower iron content (<0.055 mg/kg). In spiteof a lower metal ion content, the emulsion containing white vinegar(sample 2) was found to oxidise much faster than an identical emulsioncontaining balsamic vinegar instead of white vinegar (sample 1).

The results shown in Table 8 indicate that oxidation in the emulsioncontaining balsamic vinegar and Tween60 (sample 1) proceeds at a muchlower rate than the emulsion containing white vinegar and Tween 60(sample 2). Furthermore, these results show that in the absence of Tween60 (sample 3) the emulsion containing balsamic vinegar oxidizes at amuch higher rate than in case these emulsion additionally contains Tween60.

The effect of Tween 60 is deemed to be related to differences in thecomposition of the droplet interface and the physical location of pro-and antioxidants in the emulsion. As oxidation is initiated at theoil-water interface, both pro- and antioxidants are more effective whenthey are localised at or near the droplet surface. Emulsifiers can alterthe location and thereby promote or retard lipid oxidation.

In the absence of Tween 60 oil droplets of the emulsion containingbalsamic vinegar are believed to be covered by high molecular weightmelanoidins. As melanoidins have metal chelating properties, binding ofmetal ions by these melanoidins will cause an accumulation of metal ionsnear the oil droplet surface. This accumulation of metal ions canaccelerate the rate of oxidation and thereby counteract any positive(radical scavenging) effects of melanoidins. In the presence of Tween 60(right) emulsifier molecules will compete with surface activemelanoidins for a position at the interface. It is assumed that as aresult of this competition a major portion of the oil droplet surfacewill be occupied by Tween 60 molecules and that melanoidins (and metalions associated with them) will be mainly located in the aqueous phaseof the emulsion, away from the oil droplet surface. The lower metal ionconcentration at the oil droplet surface is believed to explain theslower oxidation in the presence of Tween 60.

Example 5

Example 4 is repeated except that this time instead of Tween 60 egg yolkis added to samples 1 and 2 (2 wt. %). Moreover the balsamic vinegarthat is used in this example 5 is the same as in example 1. Thecomposition of the samples is shown in Table 9.

TABLE 9 1 2 3 sunflower oil 10 10 10 balsamic vinegar 45 45 whitevinegar 45 egg yolk 2 2 millipore water 43 43 45

Table 10 shows the hexanal levels found in the headspace of theemulsions at different stages of the accelerated oxidation test.

TABLE 10 Time (in days) 1 2 3 0 1,862 2,069 3,041 1 5,334 147,882 18,5043 10,808 790,140 16,071 6 15,294 5,040,555 34,746 8 20,072 11,678,69255,614 10 27,648 18,097,389 108,242 13 66,731 32,264,577 194,545

The oxidation stability of sample 1 is found to be significantly higherthan that of samples 2 and 3.

The invention claimed is:
 1. A method of preparing an EDTA-freemayonnaise, said method comprising: forming a continuous aqueous phasecomprising reduced grape juice in an amount providing 5-2,000 μg gallicacid equivalents per milliliter of aqueous phase, said reduced grapejuice containing at least 50% by weight of dry matter of monosaccharidesselected from glucose, fructose and combinations thereof; a source ofacetic acid in an amount providing 0.2-15% acetic acid by weight of thecontinuous aqueous phase, said source of acetic acid containing at least20% acetic acid by weight of dry matter; and egg protein in an amount of0.02-4% by weight of the mayonnaise; and mixing an oil phase into thecontinuous aqueous phase to form the EDTA-free mayonnaise comprising5-85 wt. % of dispersed oil phase and 15-95 wt. % of continuous aqueousphase.
 2. The method according to claim 1, wherein the reduced grapejuice contains 50-50,000 μg/g gallic acid equivalents.
 3. The methodaccording to claim 1, wherein the reduced grape juice has a dry mattercontent of at least 20 wt. %.
 4. The method according to claim 1,wherein the reduced grape juice is mosto cotto.
 5. The method accordingto claim 1, wherein the reduced grape juice contains phenolic acids in aconcentration of 0.03-30 mg per g of dry matter, said phenolic acidsbeing selected from gallic acid, protocatecuic acid, p-coumaric acid,syringic acid, vanillic acid, 4-hydroxy benzoic acid, feluric acid,caffeic acid and combinations thereof.
 6. The method according to claim1, wherein the reduced grape juice contains 60-95% monosaccharides byweight of dry matter, said monosaccharides being selected from fructose,glucose and combinations thereof.
 7. The method according to claim 1,wherein the reduce grape juice contains 50-25,000 mg per kg of drymatter of Maillard reaction products selected from the group offurfural, 5-methyl-2-furaldehyde, 5-hydroxymethylfuraldehyde,5-acetoxymethylfurfural, 2-furoic acid and combinations thereof.
 8. Themethod according to claim 1, wherein the source of acetic acid isselected from the group of wine vinegar, sherry vinegar, spirit vinegar,rice vinegar, apple vinegar, malt vinegar and combinations thereof. 9.The method according to claim 1, wherein the source of acetic acidcontains less than 15% monosaccharides by weight of dry matter, saidmonosaccharides being selected from the group consisting of fructose,glucose and combinations thereof.
 10. The method according to claim 1,wherein the mayonnaise contains 0.5-10 wt. % egg yolk.
 11. The methodaccording to claim 1, wherein the reduced grape juice contains less than0.1 wt. % of substances having a molecular weight of more than 20 kDa.12. The method according to claim 1, comprising incorporating anoil-in-water emulsifier is incorporated in the mayonnaise, preferably inan amount of from 0.1 wt. % to 2 wt. % by weight of the mayonnaise. 13.The method according to claim 1, wherein the reduced grape juicecontains less than 0.05 wt. % of substances having a molecular weight ofmore than 20 kDa.
 14. The method according to claim 1, wherein thereduced grape juice contains less than 0.01 wt. % of substances having amolecular weight of more than 20 kDa.